Conventional A-B-A block copolymers are known to be useful in coatings, sealants, adhesives and modified asphalts but their usefulness in such products is not as great as it could be if these polymers did not suffer from deficiencies in certain physical properties such as creep resistance and solvent resistance. For instance, U.S. Pat. No. 3,792,005 disclosed that coatings can be made using block copolymers of A--B--A type where A is a monovinyl aromatic polymer block, usually polystyrene (S), and B is a rubber polymer block, usually hydrogenated polybutadiene (EB) or hydrogenated polyisoprene (EP). These polymers could be especially useful in elastomeric coatings because they can be formulated to have good flexibility and therefore, will not crack during thermal cycling, an important requirement for roof coatings for example, or during metal forming, where the coating becomes stretched as the metal is bent. However, coatings based on conventional A--B--A type block copolymers are deficient in that they lack strong adhesion and in applications in which the coating will contact organic liquids such as gasoline, the coatings will merely dissolve off of the substrate.
It would be advantageous to provide block polymers of this type which had increased creep and solvent resistance. By functionalizing these conventional block polymers, they can then be crosslinked to give polyurethane and polyurea structures which perform better at high temperatures and are thus more useful than the conventional block polymers in many coatings, sealants, adhesives and modified asphalt applications.